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961.
Jane M. Mutune Christian P. Hansen Raphael G. Wahome David N. Mungai 《Journal of Sustainable Forestry》2017,36(3):230-249
The study espoused the access analytical framework to investigate how introduction of Participatory Forest Management (PFM) in Kenya has changed the various actors’ ability to benefit from the forest resources of Eastern Mau Forest Reserve. Data collected through key informant interviews, and a household survey showed that implementation of PFM has triggered new income opportunities for forest adjacent communities in seedling production and beekeeping. However, PFM bestowed no real decision-making powers to the established Community Forest Associations (CFAs) over important forest resources such as timber and firewood. Members of the local communities and other actors have continued to access these resources through various structural and relational means, in the same way as before the introduction of PFM. Further, it is documented that PFM has introduced additional burdens on the local communities, especially the poorest households, as a result of increased enforcement of rules. Based on these findings, it is suggested that the PFM policy in Kenya, in its current form, is unlikely to realize its dual objectives of forest conservation and livelihood enhancement. To attain them would require a further devolution of rights to the CFAs. 相似文献
962.
963.
Linda?Meyer-VeltrupEmail authorView authors OrcID profile Christian?Brischke Gry?Alfredsen Miha?Humar Per-Otto?Fl?te Tord?Isaksson Pia?Larsson?Brelid Mats?Westin J?ran?Jermer 《Wood Science and Technology》2017,51(3):615-637
Comprehensive approaches to predict performance of wood products are requested by international standards, and the first attempts have been made in the frame of European research projects. However, there is still an imminent need for a methodology to implement the durability and moisture performance of wood in an engineering design method and performance classification system. The aim of this study was therefore to establish an approach to predict service life of wood above ground taking into account the combined effect of wetting ability and durability data. A comprehensive data set was obtained from laboratory durability tests and still ongoing field trials in Norway, Germany and Sweden. In addition, four different wetting ability tests were performed with the same material. Based on a dose–response concept, decay rates for specimens exposed above ground were predicted implementing various indicating factors. A model was developed and optimised taking into account the resistance of wood against soft, white and brown rot as well as relevant types of water uptake and release. Decay rates from above-ground field tests at different test sites in Norway were predicted with the model. In a second step, the model was validated using data from laboratory and field tests performed in Germany and Sweden. The model was found to be fairly reliable, and it has the advantage to get implemented into existing engineering design guidelines. The approach at hand might furthermore be used for implementing wetting ability data into performance classification as requested by European standardisation bodies. 相似文献
964.
Carmen Zulema Quiñones-Pérez María del Socorro González-Elizondo Christian Wehenkel 《New Forests》2017,48(2):201-215
Genetic erosion has been variously defined as the loss of particular alleles, the reduction in richness of the total number of alleles, and the reduction in evenness of the frequencies of alleles in a given place within populations or across species. Picea chihuahuana Martínez is an endangered endemic species known to occur in at least 40 locations along the Sierra Madre Occidental, in the states of Durango and Chihuahua (Mexico), but covering a total area of no more than 300 ha. The total number of individuals has been estimated to be around 42,600, and the number of mature individuals may be <2500. The populations (including mature trees, saplings and seedlings) vary in size from 21 to 5546 individuals. It has been suggested that small populations may be more susceptible to loss of genetic variability via genetic erosion caused by genetic drift, endogamy depression and strong unidirectional selection. The predicted reduction and eventual disappearance of a suitable habitat for P. chihuahuana due to climatic change imposes an additional risk of extinction. The principal aim of this study was therefore to estimate genetic erosion in 14 populations of P. chihuahuana Martínez by comparing genetic diversity across diameter at breast height classes (as a proxy for age classes) by using AFLP markers and four indices of genetic diversity that are commonly applied in combination with dominant genetic markers. No evidence of genetic erosion was found in the 14 P. chihuahuana populations analyzed. 相似文献
965.
Joseph R. Sowokinos Ryan J. Hayes Christian A. Thill 《American Journal of Potato Research》2018,95(5):487-494
Past investigations have suggested that both UGPase and AcInv activities can be used as markers to screen genetically diverse potato clones for cold induced sweetening resistance (CIS-R). The goal of this study was to define their cooperative interaction in regulating sweetening. Inter- and intra-ploidy hybridizations of good (G) and poor (P) processing 24 or 48 chromosome potato clones were used to create 24 potato families. Potatoes were field grown and 460 progeny (≤20 each family) were stored for five months in the cold (4 C). Tubers from each progeny plant were evaluated for cold induced sweetening resistance (CIS-R) and correlated with the percentage of A-II isozymes of UDP-glucose pyrophosphorylase (UGPase; EC 2.7.7.9); and acid invertase activity (AcInv; EC 3.2.1.26). Each progeny was given a CIS-R score of 1–10 (1-most resistance, 10 least resistance). The families were grouped into four classes based on (1) high or low AcInv activity (low being a SA of 0.30 or less) (2) high or low percentage of A-II isozymes (low being 50% or less), and (3) CIS-R score. In high AcInv families, CIS-R was low regardless of the percentage of A-II isozymes present. In low AcInv activity families, there was a trend for average chip color to improve as the percentage of A-II isozymes increased from 0% to 40%. This increase in CIS-R in low AcInv families is likely due to the kinetic properties unique to the A-II forms of UGPase (principally UGP5) which limit the formation of sucrose via sucrose-6-phosphate synthase (SPS; EC 2.4.1.14). Lower concentrations of sucrose can lead to a decrease in reducing sugar production via vacuolar AcInv and lighter chip and fry colors. In selecting tetraploid parents, for the development of processing potato clones with improved CIS-R, it is recommended they have a basal AcInv SA of 0.30 or less and have A-II isozymes of UGPase. 相似文献
966.
Vladimir López María Angeles Risalde Marinela Contreras Lourdes Mateos‐Hernández Joaquin Vicente Christian Gortázar José de la Fuente 《Journal of fish diseases》2018,41(10):1515-1528
Control of mycobacterial infection constitutes a priority for human and animal health worldwide. However, effective vaccines are needed for the control of human and animal tuberculosis (TB). Adult zebrafish have become a useful model for studying the pathophysiology of mycobacterial infection and for the development of novel interventions for TB control and prevention. Recently, parenteral and oral immunization with the heat‐inactivated Mycobacterium bovis vaccine (M. bovis IV) protected wild boar against TB. The objectives of this study were to provide additional support for the role of M. bovis IV in TB control using the zebrafish model and to conduct the first trial with this vaccine for the control of fish mycobacteriosis. The results showed that M. bovis IV protected zebrafish against mycobacteriosis caused by low and high infection doses of Mycobacterium marinum and provided evidence suggesting that the protective mechanism elicited by M. bovis IV in zebrafish as in other species is based on the activation of the innate immune response through the C3 pathway, with a role for the regulatory protein Akr2 in this process. These results encourage the use of M. bovis IV for TB control in different species. 相似文献
967.
Cynthia Schäfer Eric Andreas Thurm Thomas Rötzer Christian Kallenbach Hans Pretzsch 《Scandinavian Journal of Forest Research》2018,33(6):568-582
High-resolution measurements of stem radius variations provide information about the tree water status with changing climate conditions by swelling and shrinking due to the reduction of xylem water potential and to the exceedance of leaf transpiration over root water uptake. The aim of this study was to analyze daily stem radius variations of Norway spruce and European beech in intra- and interspecific neighborhood. The experimental plots are part of a rainfall exclusion experiment. These variations are species-specific, i.e. spruces have a higher phloem thickness and higher amplitudes during a day than beeches. The amplitudes were significantly higher at the rainfall exclusion plots, but the amplitudes of spruces decreased above 27°C with increasing drought due to reduced transpiration rates and exhausted soil water reserves. The shrinking amplitude was observed for spruces in intraspecific neighborhood from a soil volumetric water content of 0.21?m3?m?3. In interspecific neighborhood, a shrinking amplitude for spruces could not be observed and revealed a lesser tree water deficit than in intraspecific neighborhood. Beeches showed minor differences with a higher tree water deficit in interspecific neighborhood. Consequently, stem radius variations give insights into a tree's water supply, which could help to understand changes in tree growth. 相似文献
968.
Key message
Biomass functions are relevant for an easy and quick estimation of tree biomass. Nevertheless, additive biomass functions for different species and different components have not been published for the area of Germany, yet. Now, we present a set of additive biomass functions for estimating component and total mass for eight species and up to nine components.Context
Biomass functions are relevant for an easy and quick estimation of tree biomass, e.g. for carbon budget calculation. Component-specific functions offer even more detail and can be used to answer questions about, e.g., biomass allocation to different components, (nutrient) element stock and flows or the amount and re-distribution of harvested biomass and its consequences.Aims
Since there exists no published additive biomass functions in the context of Germany, we aimed at providing such equations for different species and different components using a comprehensive data set from different sources.Methods
We collected several data sets for eight relevant tree species (Norway spruce, n =?1150 trees; Silver fir, n =?31; Douglas fir, n =?161; Scots pine, n =?460; European beech, n =?918; Oak, n =?313; Sycamore, n =?28 and European ash, n =?37) in Germany and adjacent countries, homogenised the component information, imputed missing values and applied nonlinear seemingly unrelated regression to eight (for deciduous trees species) respectively nine (for conifereous species) components simultaneously.Results
The collected data set contains trees from 7 cm diameter in breast height to around 80 cm. From this broad data basis, we established two sets of additive biomass functions: a simple model using the predictors diameter in breast height and tree height as well as a more elaborate model using up to six predictors.Conclusion
Finally, we can present additive models for the eight relevant tree species in Germany. Models for Silver fir, European ash and Sycamore are rather limited in their model range due to their input data; the other models are based on a broad range of predictors and are considered to be broadly applicable.969.
Sabine C. HANSEN Caroline STOLTER Christian IMHOLT Jens JACOB 《Integrative zoology》2017,12(5):428-436
Rodents, including common voles (Microtus arvalis) and house mice (Mus musculus) cause immense pre‐harvest and post‐harvest losses. Therefore, developing methods that mitigate these losses while maintaining their role in ecosystems is a priority. Several plant secondary metabolites (PSM) which significantly reduce food intake of both species under laboratory conditions have been identified. However, before these can be used in rodent pest management, they must be tested under more natural conditions where other food sources are available. In this study, the odors of 4 PSMs were evaluated for their repellent effects in experiments conducted in semi‐natural enclosures. Soil treated with PSMs or untreated soil (experimental control) was placed in an underground box containing food (rolled oats). We quantified the number of visits to each box and could demonstrate that all 4 PSMs reduced the number of visits to treatment boxes in both rodent species. For common voles the combination of methyl nonyl ketone + black pepper oil was the most repellent PSM. House mice made fewer visits to all PSM boxes; boxes with the anthraquinone were visited least. Furthermore, house mice consumed less food from boxes containing soil treated with all 4 PSMs. Our results suggest that PSMs are repellent in murid and microtine rodents under semi‐field conditions. In addition, the future use of PSM odors for repelling both pest species, especially house mice, seems promising. Further investigations with other PSMs, different concentrations as well as alternative application methods are needed to repel common voles from attractive crops. 相似文献
970.
Juan Pablo Rodríguez Bo Ørting Christian Andreasen Sven-Erik Jacobsen Marten Sørensen 《Genetic Resources and Crop Evolution》2018,65(2):449-469
The leguminous Andean root crop ahipa has become scarce and the current status of in situ conservation in Bolivia is concerning. Agro-biodiversity changes affect the use, conservation and socio-economic trends for ahipa (Pachyrhizus ahipa) and to substantiate this, a comparison of two cropping periods were made. Aspects of root production and the shift from cultivation of ahipa to cash crops such as maize were compared for two periods: (a) 1994/96 and (b) 2012. Our study showed that the price of ahipa had not increased in 70% of the urban markets; hence, there is little incentive to retain the cultivation of ahipa. We found that rural ahipa growers selected the largest seeds, but did not select seeds by colour. The mixed seed colour predominated the conservation of ahipa. Laborious yield enhancing practices required in field management and low market value endanger future conservation of the ahipa. We conclude that additional research is needed in order to safeguard the extant variation of ahipa, i.e. nutritional value, taste, stress tolerance and market potential. 相似文献